The present invention relates to a blower, and more particularly, to such portable blower having a blower mode to blow away dust and the like, and a vacuum mode to suck in air to perform dust collection or the like.
The blower includes a casing formed with an inlet and an outlet and defining therein a fan housing space. A centrifugal fan including a so-called vane wheel is provided in the fan housing space. The centrifugal fan is rotatable by an electric motor for blowing out air or sucking air. The rotation of the fan simultaneously cools the motor. Upon rotation of the centrifugal fan, air is sucked into the casing through the inlet and is blown to an atmosphere through the outlet. The blower is utilized for such purposes as to blow away dusts, fallen leaves, wood chips, etc., or to suck in and collect the dusts, wood chips, etc. For blowing operation, a nozzle is attached to the outlet of the casing, whereas nothing is attached to the inlet. On the other hand, for suction operation, a dust collection bag is attached to the outlet, and a nozzle or hose is attached to the inlet.
More specifically, as shown in FIG. 18, a casing 110 is composed of a plurality of separable segments such as a mutually opposing first segment 110A and second segment (not shown), and define therein a fan housing space 110a in which a centrifugal fan 130 shown in FIG. 19 is accommodated. The first segment 110A includes a circular partition 110C defining the fan housing space 110a, and a generally cylindrical peripheral wall 110L. The centrifugal fan 130 includes a base plate 131 and multiple spiral vanes 132 projecting from one surface 131A of the base plate 131. The base plate 131 has an opposite surface 131B positioned in direct confrontation with the circular partition 110C. A plurality of through-holes 131a are formed in the base plate 131.
At the center of the partition 110C of the first segment 110A, a bearing holder 110D is provided in order to hold a bearing (not shown) which rotatably supports a rotor (not shown) of an electric motor (not shown). The centrifugal fan 130 is mounted on the rotor. Further, an outlet 112 is positioned in a tangential direction with respect to the circular partition 10C of the casing 110.
In the location which opposes the first segment 110A shown in FIG. 18, which is the location upward from the sheet of FIG. 18, the second segment (not shown) is disposed opposite to the first segment 110A. The first segment 110A and the second segment are coupled to each other at a parting face 110E. By bringing the first segment 110A and the second segment into contact with each other at the parting face 110E, the single fan housing space 110a is provided. The second segment is formed with an inlet (not shown) in order to suck air from outside the casing 110 into the fan housing space 110a. 
The inlet protrudes cylindrically from the second segment in a direction upward from the sheet of FIG. 18. A nozzle or other accessories can be attached to and detached from the inlet. An electric motor housing space (not shown) is provided on the first segment 110A on the opposite side of the fan housing space 110a with respect to the partition 110C, that is, at the location downward from the sheet of FIG. 18. The electric motor (not shown) for rotating the centrifugal fan 130 is installed in the electric motor housing space. At a radially outer side of and adjacent to the bearing holder 110D, arcuate through-holes 110c are formed in the partition 110C. Each arcuate through-hole has a contour on an imaginary circle whose center is coincident with the center of the circularly shaped partition 110C. Moreover, the arcuate through holes 110c are positioned in alignment with the plurality of through-holes 131a formed in the base plate 131. The through-holes 110c, 131a provide fluid communication between the electric motor housing space and the fan housing space 110a. 
In the blower, air flows into the inlet by the centrifugal force brought by the rotation of the centrifugal fan 130. The air flows from the upward location toward the downward location in the sheet of FIG. 19, which is the axial direction of the fan 130. The air enters the spaces between the neighboring vanes 132, and changes direction by roughly 90 degrees within the centrifugal fan 130, and flows in the radial direction of the centrifugal fan 130. The air flows following the inner peripheral surface of the peripheral wall 110L (FIG. 18), and finally flows out through the outlet 112. Incidentally, the second segment also has a peripheral wall complementary to the peripheral wall 110L.
In addition to this air flow, another flow path is provided for cooling the electric motor. The casing 110 is formed with another inlet (not shown) at a position near the electric motor. By the rotation of the fan 130, air is introduced into the electric motor housing space through the other inlet, and passes along the electric motor for cooling the electric motor. The air then passes through the arcuate through-holes 110c and the through-holes 131a, and enters into the centrifugal fan 130. Then the air changes direction by roughly 90 degrees within the centrifugal fan 130 and flows in the radial direction of the centrifugal fan 130, flows following the inner surface of the peripheral wall 110L, and flows out through the outlet 112. Such conventional blower is described in laid open Japanese Patent Application Publication No. 2002-339898. With the conventional structure, operation noise is the typical problem.